C_S_D 4430 Lecture Notes - Lecture 9: Exocytosis, Axon Hillock, Schwann Cell
Document Summary
Glial cell membranes tightly wrap around and insulate the axon. Breaks between the myelin segments are called nodes of ranvier. Nodes of ranvier contain voltage-sensitive ion channels that are absent below the myelin. Axon hillock 1st location with voltage-sensitive ion channels. Depolarization to threshold generation of initial ap at axon hillock. Current travels rapidly beneath a myelin segment via electronic conduction. Ap is regenerated at a node of ranvier where there are voltage-sensitive ion channels. This process repeats over and over until depolarization reaches the end of the axon at the bouton. The presynaptic (sending side) bouton initiates transmission of the chemical signal across the synaptic cleft (space between) The post synaptic (receiving side) surface may be part a dendrite, soma, axon, or bouton of another neuron. The bouton of one neuron makes synaptic contact with the dendrite of another: axosomatic contact. The bouton of one neuron makes synaptic contact with the soma of another: axoaxonic contact.
